Circuit breakers, sometimes referred to as circuit interrupters, include electrical contacts that connect to each other to pass current from a source to a load. The contacts may be separated in order to interrupt the delivery of current, either in response to a command or to protect electrical systems from electrical fault conditions such as current overloads, short circuits, and low level voltage conditions.
Opening the contacts in a circuit breaker can create an arc. To avoid this result, circuit breakers may use an insulated gas, oil, or a vacuum chamber in order to extinguish the current and the arc. Vacuum circuit interrupters include a separable pair of contacts positioned within an insulated and hermetically sealed vacuum chamber. The chamber is contained within a housing. Typically, one of the contacts is moveable and the other is fixed with respect to the housing, although in some vacuum interrupters both contacts may be moveable.
In certain circuits, such as medium voltage direct current (DC) circuits, it is desirable to have a vacuum circuit interrupter in which the contacts move with a fast opening speed. Some ultra-fast switching mechanisms can have opening speeds of as much as 5 meters per second (m/s), as compared to traditional vacuum circuit interrupters in which the opening speed is 0.5 to 1 m/s. However, fast opening speeds can create issues. Because the contacts' velocity of travel must remain high all the way through the contacts' end-of-travel position, contacts can slam against other parts, creating wear, bounce and other undesirable effects.
To mitigate this, in the prior art vacuum circuit interrupters have used dampers in the form of springs, rubber, and other elastic structures that serve as an energy absorber at the end of travel. However, when such materials are repeatedly compressed, their durability can deteriorate. In addition, when the movable contact hits the fixed contact it can bounce back, creating vibration and reducing the ability to precisely control movement of the moveable contact and thus the current interruption performance
This document describes methods and systems that are intended to address some or all of the problems described above.